1. Field of the Invention
The present invention relates to an image processing apparatus, an image processing system, and a recording medium for programs therefor, which are suitable for image processing of a monitoring image by a high-definition monitoring camera.
2. Description of Relevant Art
In the present day, a monitoring camera is installed at an entrance of a building and a parking area, at a gate of a factory site and a school site, and an inside of a shop such as a large-scale store and a convenience store, and a people flow is monitored in real time by a facility administrator or a security guard, and at the same time, the monitoring image is simultaneously stored in a storage medium such as a magnetic tape and a magnetic disk. A major purpose of the monitoring is to perceive a person displayed on the monitoring image as a mobile object and to identify who he/she is, as well as tracking a flow line of the person. That is, when a suspicious person is checked using a real time monitoring image, or when an accident occurred in the neighborhood, stored images in the past are used for finding and confirming a criminal.
Meanwhile, in recent years, with digitalization of a monitoring camera and a progress of high-definition technology (for example, six million pixels), a wider range of monitoring has become available, and in addition, it has become possible to obtain personal facial characteristics and expressions in detail. On the other hand, since an imaging capability of the high-definition monitoring camera exceeds a displaying capability of a common display apparatus, a whole imaged monitoring image can not be displayed on the apparatus as it is. Therefore, for displaying the whole monitoring image in one screen, the image must be displayed by lowering the resolution. In a display of low resolution, the personal facial characteristics and expressions can not be displayed in detail.
Then, for example, when finding a suspicious person, or when tracking a found suspicious person, it is necessary to restore a part of the image which includes, for example, a face of the suspicious person to the high-definition image, as needed. However, for restoring the image to the high-definition image, a display area is required to be assigned. Since a person who should be displayed with high-definition image moves by the minute in the monitoring image, a manual operation of the monitoring camera is practically impossible.
Therefore, for eliminating the above issues, for example, an example of a monitoring camera system, a slave camera is used for monitoring a part in detail is arranged in addition to a master camera which monitors a whole. And a specific part of the image, such as a human area and a facial area in the image is tracked by the slave camera as well as imaging the specific part of the image by zooming, is disclosed in a first non-patent literature, Ito et al, “An cooperative Intruder Surveillance System using Master and Slave Cameras”, Symposium on recognition and comprehension of image 2000, The Institute of Electronics, Information and Communication Engineers, Jul. 18, 2000, p.II 229-p.II 234. In addition, an automatic detection of a human face or the like is required for tracking a person or the like in the monitoring image. Examples of calculation methods for detecting a human face from a monitoring image using a computer are disclosed in a second non-patent literature, Kazui et al, “A Study of Face Detection Using Peripheral Increment Sign”, Workshop on practical application of a vision technology, The Japan Society for Precision Engineering, Dec. 2, 2004, and a third non-patent literature, Paul Viola et al, “Rapid Object Detection using a Boosted Cascade of Simple Features”, Proceedings of the 2001 IEEE Computer Society Conference on Computer Vision and Pattern Recognition, IEEE Computer Society, 2001, p.I 511-p.I 518.
In the monitoring system disclosed in the first non-patent literature, a camera number corresponding to a tracking target number is required. Therefore, if the monitoring system is applied to a place where many peoples pass through or come in and out, many slave cameras must be installed. In this case, a system cost becomes high, and practically, securing of an installation space for the slave cameras becomes hard. Accordingly, when a number of slave cameras as many as that of the monitoring targets can not be installed, a monitoring omission may happen, or a real time manual selection of the monitoring target by an observer will be required.
In addition, when the tracking targets such as faces of many peoples are automatically extracted from a high-definition monitoring image, since a processing target area is wide and the tracking targets are many, a processing time for the extraction becomes long. In this case, since a capability of the extraction processing is not sufficient for an input monitoring image which is input with a predetermined interval, a frame dropping of the monitoring image may be caused. If the frame dropping is caused, a monitoring oversight may be caused.
Meanwhile, the high-definition camera is not practically used for a monitoring camera. Therefore, there has been no proposal in the past on how to display the high-definition monitoring image on a low capability display apparatus and how to use the displayed image for the monitoring.
It is, therefore, an object of the present invention to provide an image processing apparatus, an image processing system, and a recording medium for programs therefor, which can extract a monitoring target such as a human face from a high-definition monitoring image obtained by a high-definition monitoring camera within a predetermined time without dropping frames, and can display the extracted monitoring target as a high-definition image, by considering the aforementioned conventional technical issues.